View source for 4kqw


==The structure of the Slackia exigua KARI in complex with NADP==
<StructureSection load='4kqw' size='340' side='right'caption='[[4kqw]], [[Resolution|resolution]] 1.39&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4kqw]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Slackia_exigua_ATCC_700122 Slackia exigua ATCC 700122]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4KQW OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4KQW FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.39&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=NAP:NADP+NICOTINAMIDE-ADENINE-DINUCLEOTIDE+PHOSPHATE'>NAP</scene>, <scene name='pdbligand=TLA:L(+)-TARTARIC+ACID'>TLA</scene></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=4kqw FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4kqw OCA], [https://pdbe.org/4kqw PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4kqw RCSB], [https://www.ebi.ac.uk/pdbsum/4kqw PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4kqw ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ILVC_SLAES ILVC_SLAES] Involved in the biosynthesis of branched-chain amino acids (BCAA). Catalyzes an alkyl-migration followed by a ketol-acid reduction of (S)-2-acetolactate (S2AL) to yield (R)-2,3-dihydroxy-isovalerate. In the isomerase reaction, S2AL is rearranged via a Mg-dependent methyl migration to produce 3-hydroxy-3-methyl-2-ketobutyrate (HMKB). In the reductase reaction, this 2-ketoacid undergoes a metal-dependent reduction by NADPH to yield (R)-2,3-dihydroxy-isovalerate.[HAMAP-Rule:MF_00435]<ref>PMID:23776225</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
To date, efforts to switch the cofactor specificity of oxidoreductases from nicotinamide adenine dinucleotide phosphate (NADPH) to nicotinamide adenine dinucleotide (NADH) have been made on a case-by-case basis with varying degrees of success. Here we present a straightforward recipe for altering the cofactor specificity of a class of NADPH-dependent oxidoreductases, the ketol-acid reductoisomerases (KARIs). Combining previous results for an engineered NADH-dependent variant of Escherichia coli KARI with available KARI crystal structures and a comprehensive KARI-sequence alignment, we identified key cofactor specificity determinants and used this information to construct five KARIs with reversed cofactor preference. Additional directed evolution generated two enzymes having NADH-dependent catalytic efficiencies that are greater than the wild-type enzymes with NADPH. High-resolution structures of a wild-type/variant pair reveal the molecular basis of the cofactor switch.

General approach to reversing ketol-acid reductoisomerase cofactor dependence from NADPH to NADH.,Brinkmann-Chen S, Flock T, Cahn JK, Snow CD, Brustad EM, McIntosh JA, Meinhold P, Zhang L, Arnold FH Proc Natl Acad Sci U S A. 2013 Jul 2;110(27):10946-51. doi:, 10.1073/pnas.1306073110. Epub 2013 Jun 17. PMID:23776225<ref>PMID:23776225</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 4kqw" style="background-color:#fffaf0;"></div>

==See Also==
*[[Ketol-acid reductoisomerase 3D structures|Ketol-acid reductoisomerase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Slackia exigua ATCC 700122]]
[[Category: Arnold FH]]
[[Category: Brinkmann-Chen S]]
[[Category: Brustad EM]]
[[Category: Cahn JKB]]
[[Category: Flock T]]
[[Category: Mcintosh JA]]
[[Category: Meinhold P]]
[[Category: Snow CD]]
[[Category: Zhang L]]